Diamonds, they say, are eternal. Much of the hype that surrounds these precious stones has to do with their relative rarity. According to a new study, however, they may be far more common than previously thought. Before you rush to your local jewelry store, it will be wise to heed the scientists’ prediction: most of these diamonds are likely present so far below the Earth’s surface that it will be almost impossible to extract them physically.
Up until now, it was believed that diamonds are formed via one of the following two ways: the movement of fluid as a result of the oxidation of methane or the reduction of carbon dioxide. Diamond formation is directly related either to oxidation, which entails an increase in the number of electrons, or reduction to a lower oxidation state. What is more, the process requires a specific set of geochemical circumstances, including extremely high temperatures and pressures, which in turn add to the rarity of these precious stones.
As part of a new study, recently published in the Nature Communications journal, scientists at John Hopkins University have uncovered a far simpler process by which diamonds could be produced. According to the research, a natural chemical reaction between water and rock could lead to the formation of these precious stones. Using special chemical models, the researchers showed that a drop in the water’s pH level from alkaline to acidic, while flowing through one type of rock to the other, could cause diamonds to form. Speaking about the find, Dimitri A. Sverjensky, a professor of geochemistry at John Hopkins and the study’s co-author, said:
Diamond formation in the deep Earth, the very deep Earth, may be a more common process than we thought… The more people look, the more they’re finding diamonds in different rock types now. I think everybody would agree there’s more and more environments of diamond formation being discovered.
These diamonds, the scientists believe, are formed approximately 90 to 120 miles (around 145 to 193 km) below the Earth’s surface, under incredibly high pressures and temperatures of about 1,600 to 2,000 °F. Most diamond drilling explorations can only reach to a depth of around 8 to 9 miles (approx. 13 to 14 km) below the surface. Readily-extractable diamonds are usually the result of extremely rare magma eruptions, which in turn push the Earth’s deep interior outwards.
It is highly unlikely that the abundance of these precious stones in the deep Earth would have any effect on the diamond industry. This is because most of them are only a few microns in size, and would therefore be invisible to the naked eye. While the findings have not yet been empirically confirmed, the researchers believe that the study could shed more light on the complex fluid dynamics of the Earth’s interior. Sverjensky, who worked alongside doctoral student Fang Huang, said:
Fluids are the key link between the shallow and the deep Earth. That’s why it’s important.